Studies on Agrobacterium-mediated genetic transformation of embryogenic suspension cultures of sweet potato

In this study, genetic transformation of embryogenic suspension cultures of sweet potato (Ipomoea batatas) cultivar Xu55-2 was conducted utilizing the Agrobacterium tumefaciens strain EHA105 thatcontains the binary vector pBIN19/SBD2 with SBD2 (starch binding domain 2) gene and neomycin phosphotransferase (NPT II) gene. The presence of the SBD2 gene in the genomic DNA of transgenicplants was verified by PCR amplification and confirmed by Southern blot analysis. Results suggested that cefotaxime (Cefo), at the concentration of 200 mg/L, was able to effectively suppress the growth ofAgrobacterium after co-cultivation. The optimal concentration for kanamycin (Kan) was 10 mg/L for selecting resistance calli, somatic embryo formation and plant regeneration. The highest frequency ofshoot induction (30.9%) was obtained on the MS medium containing 10 mg/L Kan, 200 mg/L Cefo, 1.0 mg/L abscisic acid (ABA) and 1.0 mg/L gibberellic acid (GA3)

Optimization of Agrobacterium-mediated transformation parameters for sweet potato embryogenic callus using &#946-glucuronidase (GUS) as a reporter

Agrobacterium-mediated transformation factors for sweet potato embryogenic calli were optimized using -glucuronidase (GUS) as a reporter. The binary vector pTCK303 harboring the modified GUS genedriven by the CaMV 35S promoter was used. Transformation parameters were optimized including bacterial concentration, pre-culture period, co-cultivation period, immersion time, acetosyringone (AS)concentration and mannitol treated time. Results were obtained based on the percentage of GUS expression. Agrobacterium tumefaciens strain EHA105 at concentration OD600 nm = 0.8 showed the highest virulence on sweet potato embryogenic callus. Four days of pre-culture, four days ofco-cultivation, 10 min of immersion, 200 M acetosyringone and 60 min of mannitol-treated embryogenic callus gave the highest percentage of GUS positive transformants

Wiener–Khinchin Theorem in a Reverberation Chamber

IEEE The use of the Wiener–Khinchin theorem in the reverberation chamber reveals the relationships between a number of important parameters—the coherence bandwidth and the Q-factor measured in the time domain, the coherence time and the Q-factor measured in the frequency domain, the K-factor and the Doppler spectrum, and the K-factor and the total scattering cross section. The lower bound of the average K-factor is also given. Different physical quantities, which share similar mathematical insights, are unified. Analytical derivations are given, and results are validated by measurements

Genome-Wide Localization of Protein-DNA Binding and Histone Modification by a Bayesian Change-Point Method with ChIP-seq Data

Next-generation sequencing (NGS) technologies have matured considerably since their introduction and a focus has been placed on developing sophisticated analytical tools to deal with the amassing volumes of data. Chromatin immunoprecipitation sequencing (ChIP-seq), a major application of NGS, is a widely adopted technique for examining protein-DNA interactions and is commonly used to investigate epigenetic signatures of diffuse histone marks. These datasets have notoriously high variance and subtle levels of enrichment across large expanses, making them exceedingly difficult to define. Windows-based, heuristic models and finite-state hidden Markov models (HMMs) have been used with some success in analyzing ChIP-seq data but with lingering limitations. To improve the ability to detect broad regions of enrichment, we developed a stochastic Bayesian Change-Point (BCP) method, which addresses some of these unresolved issues. BCP makes use of recent advances in infinite-state HMMs by obtaining explicit formulas for posterior means of read densities. These posterior means can be used to categorize the genome into enriched and unenriched segments, as is customarily done, or examined for more detailed relationships since the underlying subpeaks are preserved rather than simplified into a binary classification. BCP performs a near exhaustive search of all possible change points between different posterior means at high-resolution to minimize the subjectivity of window sizes and is computationally efficient, due to a speed-up algorithm and the explicit formulas it employs. In the absence of a well-established "gold standard" for diffuse histone mark enrichment, we corroborated BCP's island detection accuracy and reproducibility using various forms of empirical evidence. We show that BCP is especially suited for analysis of diffuse histone ChIP-seq data but also effective in analyzing punctate transcription factor ChIP datasets, making it widely applicable for numerous experiment types